U.S. Published Application No. 2008/0134966 (the '966 application) discloses a width adjustable multi-slot applicator or gun. The disclosure of the '966 application is hereby fully incorporated by reference herein. This existing gun incorporates a nozzle having multiple fluid outlet channels spaced apart from each other and receiving pressurized fluid from a common distribution passage or channel. A movable piston is positioned for lengthwise movement in the distribution channel. The piston is used to modify the fluid application pattern and, in particular, the width of the application pattern. For this purpose, the slit between the nozzle opening and the distribution channel is segmented by the respective outlet channels. Therefore, flow components in the longitudinal or lengthwise direction of the slit can be largely prevented and this results in more uniform fluid application when orienting the nozzle vertically. The piston is used to select which of the outlet channels have adhesive flowing through them. The outlet channels located in the section of the distribution channel sealed off by the piston are prevented from receiving fluid. In this manner, the width of fluid application is variable in steps as determined by the number of outlet channels that are not blocked off by the piston.
One challenge experienced with apparatus of the above-described type is that residual adhesive will exit the outlet channels for a short period of time immediately after the main valve of the applicator is closed. Then, upon restart of the applicator, the next substrate or substrates in the production run may not receive adequate adhesive. It would therefore be desirable to prevent this from occurring and provide a system and method whereby substrates immediately after a production stoppage continue to receive uniform application of adhesive.